A broad-based research project is proposed where the general goal is to contribute to the development of quantitative models of information processing by the auditory system. The work will aim towards a general statistical decision theory formulation which can predict receiver operating characteristics and psychometric functions for many binaural and monaural psychoacoustic experiments. Related work for the visual system is also considered. Both the theoretical and experimental work derive from considerations of the functional form of the operations presumed to be carried out by the receiver, the nature of (necessary) assumptions regarding the structure and role of "internal" (biological) noise neurophysiological interpretations, adaptive (learning) effects on choice of decision strategies by individual listeners, and nonsensory variables such as attention and memory.